1. Field
Embodiments of the invention are broadly directed to the determination of an amount of fuel within a fuel system. More specifically, embodiments of the invention are directed to the determination of fuel level via a comparative fuel probe.
2. Related Art
Detecting a fuel level within a fuel tank can be problematic, especially within an exemplary field of aircraft. Detecting an accurate fuel level is of critical importance based upon the danger to the aircraft and the people on board that can result from a failed or inaccurate reading. For many years, capacitive fuel gauges have become the standard in aviation for the detection of fuel level. Capacitive fuel gauges operate by measuring the capacitance between various probes. The fuel is, in essence, working as the dielectric between the probes. The amount of fuel is therefore indicated by the detected capacitance of the summation of all tank probes.
While these capacitive fuel systems can be very accurate, they present numerous disadvantages. First, in order to accurately approximate fuel based upon capacitance, numerous factors must be determined and accounted for in calculation. These factors include permittivity of the fuel (the ability of the fluid to carry an electrical charge, which will vary by fuel blends and additives), the density of the fuel (based upon the various fuel blends and the amount of air contained within the fuel), the temperature of the fuel, the presence of corrosion on the fuel probe, the percentage of humidity or concentration of inerting gas present in the fuel or the fuel tank, the cleanliness of the fuel sensors, the motion of the fuel (based upon the flight dynamics of the vehicle), etc. Second, the sensors and processing equipment that account for the above-discussed factors are excessively heavy and complex. For example, in a large commercial aircraft these various sensors and processors can weigh between fifty and one hundred pounds. The aircraft may additionally have a mechanical drip stick system as an emergency, redundant backup that can be utilized upon failure of the capacitive system.